Laser assisted cataract surgery

ABSTRACT

Laser assisted cataract surgery methods and devices utilizing one or more treatment laser beams to create a shaped opening in the anterior lens capsule of the eye when performing a capsulorrhexis procedure. A light absorbing agent may optionally be added onto or into the lens capsule tissue, and the treatment laser wavelength selected to be strongly absorbed by the light absorbing agent. Alternatively, the treatment laser wavelength may be selected to be absorbed or strongly absorbed by the tissue itself, in which case no additional light absorbing agent need be used. Visualization patterns produced with one or more target laser beams may be projected onto the lens capsule tissue to aid in the procedure. The devices may be attached to or integrated with microscopes.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is related to the following co-filed USnon-provisional patent applications: U.S. patent application Ser. No.14/193,630 titled “Laser Assisted Cataract Surgery”, U.S. patentapplication Ser. No. 14/193,671 titled “Laser Assisted CataractSurgery”, and U.S. patent application Ser. No. 14/193,716 titled “LaserAssisted Cataract Surgery”; each of which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The invention relates generally to laser assisted ophthalmic surgery,and more particularly to methods and devices using one or more lasers inperforming a capsulorrhexis.

BACKGROUND

Cataracts are a common cause of poor vision and are the leading cause ofblindness. There are at least 100M eyes with cataracts causing visualacuity of less that 6/60 in meters (or 20/200 in feet). Cataractextraction is the most commonly performed surgical procedure in theworld with estimates of over 22 million cases worldwide and over 3million cases being performed annually in North America. Generally,there are two types of cataract surgery: small incision cataract surgerywith phacoemulsification, and extra-capsular cataract extraction.

In small incision cataract surgery with phacoemulsification, the morecommon approach, about a 2 millimeter (mm) incision is made in thecornea and the opacified natural lens is removed with irrigation,aspiration, and phacoemulsification while leaving the elastic lenscapsule intact to allow implantation and retention of an intraocularlens (IOL). Currently, extra-capsular cataract extraction surgery is amore invasive procedure and is performed in the developing countrieswhere there are fewer resources. In this procedure a large incision of 6mm or more is made in the sclera, and the complete opacified naturallens is removed.

One of the more critical components of both of these surgical proceduresis the capsulorrhexis, which is the incision in the lens capsule made topermit removal of the lens nucleus and cortex. The lens capsule is atransparent, homogeneous basement membrane that comprises collagen. Ithas elastic properties without being composed of elastic fibers. Thecapsule has a smooth surface contour except at its equator where zonulesattach.

Typically the capsulorrhexis creates a symmetric circular incision,centered about the visual axis and sized appropriately for the IOL andthe patient's condition. The mechanical integrity around the newlyformed incision edge needs to be sufficient to withstand the forcesexperienced during cataract extraction and IOL implantation.Postoperatively, the newly formed capsule rim hardens and the openingcontracts, providing further strength and structural support for the IOLto prevent dislocation and misalignment.

The current standard of care for capsulorrhexis is ContinuousCurvilinear Capsulorrhexis (CCC). The concept of CCC is to provide asmooth continuous circular opening through the anterior lens capsule forphacoemulsification and insertion of the intraocular lens, minimizingthe risk of complications including errant tears and extensions.Currently, the capsulorrhexis is performed manually utilizing forceps ora needle. This technique depends on applying a shear force andminimizing in-plane stretching forces to manually tear the incision. Onecomplication that may develop when performing a capsulorrhexis in thismanner is an errant tear. Errant tears are radial rips and extensions ofthe capsulorrhexis towards the capsule equator. If an errant tearencounters a zonular attachment the tear may be directed out to thecapsular fornix and possibly through to the posterior of the capsule.Posterior capsule tears facilitate the nucleus being “dropped” into theposterior chamber, resulting in further complications.

Further problems that may develop in capsulorrhexis are related toinability of the surgeon to adequately visualize the capsule due to lackof red reflex (reddish reflection of light from the retina), to grasp itwith sufficient security, or to tear a smooth symmetric circular openingof the appropriate size. Additional difficulties may relate tomaintenance of the anterior chamber depth after initial opening, smallsize of the pupil, or the absence of a red reflex due to the lensopacity. Additional complications arise in older patients with weakzonules and very young children that have very soft and elasticcapsules, which are very difficult to mechanically rupture.

Following cataract surgery there is a rapid 1-2 day response where thecapsule hardens and capsule contraction starts. This contractioncontinues over a 4-6 week period where fibrosis of the capsulorrhexisand IOL optic interface and of the IOL haptic and capsule interfacesalso occurs. Even beyond one year the capsule continues to contract to alesser degree. Thus positioning the capsulorrhexis is a critical factorin the long-term success.

Accordingly, there is a need in the art to provide new ophthalmicmethods, techniques and devices to advance the standard of care forcapsulorrhexis.

SUMMARY

This specification discloses laser assisted ophthalmic surgery methodsand devices.

In one aspect, a device for creating an opening in the anterior lenscapsule of the eye comprises a scanning treatment laser beam having aprogrammed scan profile for a predetermined treatment pattern that formsa closed curve at the anterior lens capsule. The treatment laser has awavelength selected to be strongly absorbed at the anterior lens capsuleand a power selected to cause thermal denaturing of collagen in theanterior lens capsule resulting in thermal tissue separation along theclosed curve without ablating anterior lens capsule tissue. The devicealso comprises a scanning visualization laser beam having a programmedscan profile for a predetermined visualization pattern at the anteriorlens capsule and a wavelength in the visible spectrum.

The visualization pattern differs from the treatment pattern in size andgeometry. At least a portion of the visualization pattern may, forexample, indicate desired boundaries of the opening to be created in theanterior lens capsule and thereby facilitate aligning the treatmentpattern on the anterior lens capsule. Typically, the desired boundariesof the opening differ in location from the closed curve of the treatmentpattern as a result of contraction of anterior lens capsule tissueadjacent to the closed curve during and after thermal tissue separation.Alternatively, or in addition, at least a portion of the visualizationpattern may correspond to one or more anatomical features of the eye,and thereby facilitate aligning the treatment pattern with respect tothose anatomical features.

In another aspect, a device for creating an opening in the anterior lenscapsule of the eye comprises a treatment laser beam and atwo-dimensional scanner on which the treatment laser beam is incident.The scanner has a programmed scan profile for a predetermined treatmentpattern in which the treatment laser beam is scanned to form a closedcurve at the anterior lens capsule. The device comprises a lenspositioned to focus the treatment laser beam to a waist at the anteriorlens capsule, with the treatment beam expanding from its waist to bedefocused on the retina of the eye. The treatment pattern passes througha treatment pattern invariant and/or a treatment pattern waist betweenthe lens and the eye. The treatment laser beam has a wavelength selectedto be strongly absorbed at the anterior lens capsule and a powerselected to cause thermal denaturing of collagen in the anterior lenscapsule resulting in thermal tissue separation along the closed curve ofthe treatment pattern without ablating anterior lens capsule tissue.

The treatment pattern may diverge in the eye and consequently beexpanded in size and area on the retina compared to its size and area atthe anterior lens capsule. As a result, the treatment pattern may avoidthe fovea on the retina.

In another aspect, a device for creating an opening in the anterior lenscapsule of the eye comprises a continuous wave scanning treatment laserbeam having a programmed scan profile for a predetermined treatmentpattern forming a closed curve at the anterior lens capsule in a singlepass. The treatment laser has a wavelength selected to be stronglyabsorbed at the anterior lens capsule, and a power selected to causethermal denaturing of collagen in the anterior lens capsule resulting inthermal tissue separation along the closed curve without ablatinganterior lens capsule tissue. At the beginning of the treatment patternthe power of the treatment laser ramps up from about zero to about 90%of its full power during a period of about 5 milliseconds to about 200milliseconds. This ramp-up may minimize the likelihood of the capsuletearing at the starting point of the treatment pattern by allowing thetissue near the starting point of the pattern to initially stretchwithout separating, thereby reducing the shear stress/tension at thestart of the pattern, and/or by avoiding or minimizing local shock wavesin the fluid adjacent to the target tissue that might otherwise begenerated by the growth and collapse of one or more vapor bubblesaccompanying a faster thermal turn-on.

In another aspect, a device for creating an opening in the anterior lenscapsule of the eye comprises a treatment laser beam and atwo-dimensional scanner on which the treatment laser beam is incident.The scanner has a programmed scan profile for a predetermined treatmentpattern in which the treatment laser beam is scanned to form a closedcurve at the anterior lens capsule. The device comprises a lenspositioned to focus the treatment laser beam to a waist at the anteriorlens capsule, with the treatment laser beam expanding from its waist tobe defocused on the retina of the eye. The treatment laser beam has awavelength selected to be strongly absorbed at the anterior lens capsuleand a power selected to cause thermal denaturing of collagen in theanterior lens capsule resulting in thermal tissue separation along theclosed curve of the treatment pattern without ablating anterior lenscapsule tissue. The device also comprises a first visible lightvisualization laser beam sharing an optical path with the treatmentlaser beam, and a second visible light visualization laser beamintersecting the first visualization laser beam at or approximately atthe waist of the treatment laser beam.

The first visualization laser beam and the second visualization laserbeam may be produced, for example, from a single visible light laserbeam incident on the scanner by dithering the scanner between theoptical path of the first visualization laser beam and the optical pathof the second visualization laser beam.

These and other embodiments, features and advantages of the presentinvention will become more apparent to those skilled in the art whentaken with reference to the following more detailed description of theinvention in conjunction with the accompanying drawings that are firstbriefly described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a transverse plane view of some parts of an eye (lenscapsule 110, dilated iris 140, cornea 160 and anterior chamber 170), thenatural crystalline lens location and the intended location of animplanted intraocular lens 120, a light absorbing agent 130, and atreatment light beam 150 to be used in an example of the capsulorrhexisprocedure described herein.

FIG. 2 shows a side view of the lens capsule 110 of FIG. 1 wherein lenscapsule 110 has been separated at location 210 into two parts, e.g. anexterior part 110-E and an interior part 110-1, by a laser based methodas described herein. This figure also shows the contracted and shrunkenends 220-E and 220-I bordering the separation.

FIGS. 3A-3H show a view from the anterior direction of a lens capsuleillustrating an example “Interior-Closed-Curve-Interior” treatmentpattern in which the treatment laser beam is directed along apredetermined closed curve 310.

FIGS. 4A-4G show a view from the anterior direction of a lens capsuleillustrating an example “Interior-Closed-Curve” treatment pattern inwhich the treatment laser beam is directed along a predetermined closedcurve 410.

FIGS. 5A-5H show a view from the anterior direction of a lens capsuleillustrating an example “Interior-Closed-Curve-Overlap” treatmentpattern in which the treatment laser beam is directed along apredetermined closed curve 410.

FIGS. 6A-6G show a view from the anterior direction of a lens capsuleillustrating an example “Closed-Curve-Overlap” treatment pattern inwhich the treatment laser beam is directed along a predetermined closedcurve 610.

FIGS. 7A-7H show a view from the anterior direction of a lens capsuleillustrating an example “Interior-Closed-Curve-Overlap-Interior”treatment pattern in which the treatment laser beam is directed along apredetermined closed curve 710.

FIG. 8 shows a view of the eye with the limbus 810, iris 140, exteriorboundary of the iris 820, pupil 190, and a visualization patterncomprising a predetermined closed curve and at least three dots 830 thatare used to assist in locating the position of the desiredcapsulorrhexis.

FIGS. 9A-9B show views of the eye including the limbus 810, iris 140,and pupil 190 on which are superimposed two additional examplevisualization patterns, each of which comprises two circles or closedcurves.

FIG. 10A-10B show views of the eye including the limbus 810, iris 140,and pupil 190 on which are superimposed two additional examplevisualization patterns, each of which comprises two circles or closedcurves with dots on the curves.

FIGS. 11A-11B show views of the eye including the limbus 810, iris 140,and pupil 190 on which are superimposed two additional examplevisualization patterns, each of which comprises a cross-hair and twocircles or closed curves with dots on the curves.

FIGS. 12A-12L show additional visualization patterns each of which maycomprise a combination of closed curves, dots on the curves, and across-hair.

FIGS. 13A-13B show an example of an elliptical rhexis with a major and aminor axis and a rotation angle. FIGS. 13C-13D show two examples ofvisualization patterns that may be used with the elliptical rhexis ofFIGS. 13A-13B. Each pattern comprises a circular outer closed curve andan elliptical inner closed curve.

FIG. 14 shows a view of the eye with the limbus 810, iris 140, exteriorboundary of the iris 820, dilated pupil 190, a visualization patterncomprising a cross-hair and two circles with dots on the curves, and atreatment beam pattern for a circular rhexis.

FIG. 15 shows a view of the eye with the limbus 810, iris 140, exteriorboundary of the iris 820, and dilated pupil 190, a visualization patterncomprising a cross-hair an outer circle with dots, and an inner ellipsewith dots, and a treatment beam pattern for an elliptical rhexis.

FIG. 16 shows a plot of power versus time for an example treatment laseroutput pulse delivered to the collagen containing tissue that may beused in the devices and methods described herein.

FIG. 17 illustrates the dependence of the power as a function ofirradiated area required to achieve thermal separation of the anteriorcapsule in the eye. The power has a low dependence at the smaller areas,and as the area increases there is a greater dependence of power on theirradiated area.

FIGS. 18A-18C show three example ray traces of a scanned laser beamdirected into an eye through the cornea and the lens and onto theretina, and the resulting projection of the scanned laser beam on theretina. FIG. 18A shows a ray trace in the absence of a surgical contactlens, and FIGS. 18B-18C show ray traces in the presence of two differentsurgical contact lenses.

FIG. 19 shows elements of an example device that may be used to scanlaser beams in an eye to perform ophthalmic surgeries as describedherein.

FIG. 20 shows the example device of FIG. 19 externally integrated with amicroscope as an attachment to the microscope.

FIG. 21 shows the example device of FIG. 19 internally integrated with amicroscope, with a shared illumination mirror and microscope objective.

FIG. 22 shows another example device similar to that of FIG. 19 but alsoincluding optical elements facilitating depth alignment with respect tothe tissue to be treated.

FIGS. 23A-23C show views of two superimposed visualization patternsproduced by the device of FIG. 22 as the depth alignment of the deviceis adjusted.

FIGS. 24A-24B show two example foot-operable controls that may be usedto control the device of FIG. 22.

DETAILED DESCRIPTION

The following detailed description should be read with reference to thedrawings, in which identical reference numbers refer to like elementsthroughout the different figures. The drawings, which are notnecessarily to scale, depict selective embodiments and are not intendedto limit the scope of the invention. The detailed descriptionillustrates by way of example, not by way of limitation, the principlesof the invention. This description will clearly enable one skilled inthe art to make and use the invention, and describes severalembodiments, adaptations, variations, alternatives and uses of theinvention, including what is presently believed to be the best mode ofcarrying out the invention. As used in this specification and theappended claims, the singular forms “a,” “an,” and “the” include pluralreferents unless the context clearly indicates otherwise.

As described in more detail below, this specification disclosesophthalmic surgery methods and devices that utilize one or moretreatment laser beams to create a shaped opening in the anterior lenscapsule of the eye when performing a capsulorrhexis procedure. In theprocedure, a light absorbing agent may optionally be added onto or intothe lens capsule tissue, and the treatment laser wavelength selected tobe strongly absorbed by the light absorbing agent. Alternatively, thetreatment laser wavelength may be selected to be absorbed or stronglyabsorbed by the tissue itself, in which case no additional lightabsorbing agent need be used. In either case, as used herein the phrase“strongly absorbed” is intended to mean that transmission of thetreatment beam through the tissue to be treated (e.g., the anterior lenscapsule) is less than about 65%, or less than about 40%. The treatmentlaser beam is directed at the lens capsule tissue along a predeterminedclosed curve to cause a thermal effect in the tissue resulting inseparation of the tissue along the laser beam path. The predeterminedclosed curve may have, for example, a circular or elliptical shape. Anyother suitable shape for the closed curve may also be used. Typically,the shape is selected to reduce the likelihood of tears developingduring cataract surgery, on the edge of the separated edge of the tissuethat is formed exterior to the closed curve. Visualization patternsproduced with one or more target laser beams may be projected onto thelens capsule tissue to aid in the procedure.

General aspects of these methods and devices may be better understoodwith reference to FIG. 1 and FIG. 2. FIG. 1 shows, in a transverse planeview of an eye, the intended location of an intraocular lens 120 to beimplanted after a capsulorrhexis procedure. In the illustrated example,a light absorbing agent 130 is added into or onto a layer of theanterior lens capsule 110. This agent may be a biocompatible agent (e.g.Indocyanine green or Trypan Blue), a dye, pigment, a nanoparticle, acarbon particle, or any other suitable light absorbing agent. The lightabsorbing agent may be Trypan Blue, other Vital Dyes, or IndocyanineGreen, for example. Subsequently, a light beam 150, e.g. a laser beam,is directed along a closed curve path on the anterior lens capsule. Thedirected light beam is absorbed by the light absorbing agent to depositthermal energy in and cause a local thermal affect on the anterior lenscapsule to yield a capsulorrhexis.

Referring now to FIG. 2, generally the wavelength, power, speed of lightbeam movement along the closed curve, and spot size on the treatedtissue are selected so that the light beam can be absorbed by the lightabsorbing agent to deposit sufficient thermal energy adjacent to or atthe anterior lens capsule to cause a mechanical separation 210 in theanterior lens capsule. The laser beam parameters are typically selectedto avoid ablation of the tissue, and the mechanical separation isbelieved to result instead from thermal denaturing of collagen in thetissue (in which, for example, the collagen transitions from acrystalline helical structure to an amorphous structure). The denaturedcollagen shrinks and contracts to form thickened rims 220-E and 220-1bordering the separation forming the capsulorrhexis. Advantageously,these rims may be more elastic and resistant to tearing than theoriginal membrane.

For clarity and convenience, various features and aspects of theinventive methods and devices are described below under separatelylabeled headings. This organization of the description is not meant tobe limiting. Variations of the methods and devices described herein mayinclude or employ any suitable combination of aspects or featuresdescribed under the separate headings.

Treatment Beam Patterns

FIGS. 3A-3H illustrate an example “Interior-Closed-Curve-Interior”treatment pattern in which the treatment laser beam is directed along apredetermined closed curve 310. The treatment pattern starts interior tothe closed curve, progresses around the closed curve, then terminatesinterior to the closed curve. Although illustrated as clockwise, thispattern may also be counterclockwise. Dashed line 310 of FIG. 3Arepresents the complete pattern. The dot 320 in FIG. 3B indicates thestart point of the pattern on the interior of the closed curve, andFIGS. 3C-3H illustrate the progression of the pattern with a solid line330 at subsequent time intervals through the delivery of the pattern.Dot 340 in FIG. 3H indicates the end point of the treatment pattern onthe interior of the closed curve. Locating the start and end points ofthe procedure on the interior of the closed curve (in material whichwill be removed from the eye) helps prevent irregularities in the shapeof the curve that might promote tearing of the rim of the remaininganterior lens capsule located exterior to the closed curve.

FIGS. 4A-4G illustrate an example “Interior-Closed-Curve” treatmentpattern in which the treatment laser beam is directed along apredetermined closed curve 410. The treatment pattern starts interior tothe closed curve, progresses around the closed curve, and thenterminates on the closed curve. Although illustrated as clockwise, thispattern may also be counterclockwise. Dashed line 310 of FIG. 4Arepresents the complete pattern. The dot 320 in FIG. 4B indicates thestart point of the pattern on the interior of the closed curve, andFIGS. 4C-4G illustrate the progression of the pattern with a solid line330 at subsequent time intervals through the delivery of the pattern.Dot 440 in FIG. 4G indicates the end point of the treatment pattern onthe closed curve.

FIGS. 5A-5H illustrate an example “Interior-Closed-Curve-Overlap”treatment pattern in which the treatment laser beam is directed along apredetermined closed curve 410. The treatment pattern starts in theinterior region of the closed curve, progresses around the closed curvewith a region of overlap on the closed curve, and then terminates on theclosed curve. Although illustrated as clockwise, this pattern may alsobe counterclockwise. Dashed line 410 of FIG. 5A represents the completepattern. The dot 320 in FIG. 5B indicates the start point of the patternon the interior of the closed curve, and FIGS. 5C-5H illustrate theprogression of the pattern with a solid line 330 at subsequent timeintervals through the delivery of the pattern. Dot 540 in FIG. 5Hindicates the end point of the treatment pattern on the closed curve,where the region 550 on the closed curve experiences treatment exposureof the laser near the beginning of the pattern, and again towards thelater part of the pattern delivery, i.e., it is the overlap region.

FIGS. 6A-6G illustrate an example “Closed-Curve-Overlap” treatmentpattern in which the treatment laser beam is directed along apredetermined closed curve 610. The treatment pattern starts on theclosed curve, progresses around the closed curve with a region ofoverlap on the closed curve, and then terminates on the closed curve.Although illustrated as clockwise, this pattern may also becounterclockwise. Dashed line 610 of FIG. 6A represents the completepattern. Dot 620 in FIG. 6B indicates the start point on the closedcurve, and FIGS. 6C-6G illustrate the progression of the pattern with asolid line 330 at subsequent time intervals through the deliver of thepattern. Dot 540 in FIG. 6G indicates the end point of the treatmentpattern on the closed curve, where the region 550 on the closed curveexperiences treatment exposure of the laser near the beginning of thepattern, and again towards the later part of the pattern delivery, i.e.,it is the overlap region.

FIGS. 7A-7H illustrate an example“Interior-Closed-Curve-Overlap-Interior” treatment pattern in which thetreatment laser beam is directed along a predetermined closed curve 710.The treatment pattern starts interior to the closed curve, thenprogresses around the closed curve with a region of overlap on theclosed curve, and then terminates on the interior of the closed curve.Although illustrated as clockwise, this pattern may also becounterclockwise. Dashed line 710 of FIG. 7A represents the completepattern. Dot 320 in FIG. 7B indicates the start point on the interior ofthe closed curve, and FIGS. 7C-7H illustrate the progression of thepattern with a solid line 330 at subsequent time intervals through thedelivery of the pattern. As shown in FIGS. 7G-7H, region 550 on theclosed curve experiences treatment exposure of the laser near thebeginning of the pattern, and again towards the later part of thepattern delivery, i.e., it is the overlap region. Dot 340 in FIG. 7Hindicates the end point of the treatment pattern on the interior of theclosed curve.

Any other suitable treatment beam patterns may also be used. One or moretreatment beam pattern shapes may be preprogrammed into a lasercapsulorrhexis device (described in more detail below) by themanufacturer, for example. At or prior to the time of treatment anoperator may then, for example, select the size (e.g., diameter) andshape of the closed curve defining the treatment pattern, or of thedesired rhexis to be produced by the closed curve of the treatmentpattern.

Visualization/Target Patterns

As noted above, visualization patterns produced with one or more laserbeams, which typically differ in wavelength from the treatment beam, maybe projected onto the lens capsule tissue to aid in the treatmentprocedure. The shape and diameter of the visualization pattern maydiffer from that of the treatment beam pattern. Although thevisualization pattern or portions of the visualization pattern mayoverlie the closed curve of the treatment pattern to indicate at leastportions of the path to be taken by the treatment beam, this is notrequired. Instead, or in addition, at least part of the visualizationpattern may overlie the intended location of the outer rim of theopening that will be produced by the tissue-separating treatment beam,or otherwise indicate the desired outcome of the treatment. The locationof that outer rim typically differs from and is of larger diameter thanthe closed curve of the treatment beam pattern for two reasons: (i) thelens capsule tissue is under tension when in the eye (very much like adrum skin), so as the tissue along the closed curve is separated theexterior portion is under tension and pulled peripherally, thusenlarging the diameter; (ii) the mechanism of action for the treatmentlaser is to locally heat the irradiated anterior capsule on a closedcurve, this heating tends to cause the collagen tissue to contract,shrink, and separate exteriorly and interiorly away from the heatedclosed curve. Alternatively, or in addition, at least part of thevisualization pattern may correspond to one or more particularanatomical features of the eye. This may facilitate centering of thevisualization pattern (and thus the treatment beam pattern) on theanatomy of the eye, or otherwise facilitate aiming the visualization andtreatment beams. The visualization pattern may optionally include across-hair.

FIG. 8 illustrates an example visualization pattern 830 comprising aclosed curve and at least three dots that may be used to assist inlocating the desired location for a capsulorrhexis. The figure alsoidentifies the limbus 810, iris 140, interior boundary of the iris 820,and pupil 190 of the eye to be treated.

FIGS. 9A-9B each show a view of an eye including the limbus 810, iris140, and pupil 190 onto which is projected an example visualizationpattern 900 comprising two concentric circles or closed curves 910 and920. The inner circle or closed curve 910 represents the size andlocation of the desired opening in the anterior capsulorrhexis. Theouter circle 920, which may be sized independently of the inner circlesize, may be used to center the capsulorrhexis on the limbus asillustrated in FIG. 9A. Alternatively, the outside circle may be sizedto allow the centering on the interior boundary of the dilated pupil, asrepresented in FIG. 9B.

FIGS. 10A-10B each show a view of an eye including the limbus 810, iris140, and pupil 190 onto which is projected an example visualizationpattern 1000 comprising two concentric circles or closed curves 1010 and1020 with dots 1030 on the curves. The combination of straight and/orcurved lines and dots provides a pattern easily focused on the targettissue. The lines are produced by moving the visualization beam alongthe desired pattern. The dots are produced by dwelling the visualizationbeam for longer periods at the dot locations in the scan pattern. Thedots may provide enhanced visualization on the target tissue becausethey are more intense than the lines. The inner circle or closed curve1010 represents the size and location of the desired opening in theanterior capsulorrhexis. The outer circle 1020, which may be sizedindependently of the inner circle size, may be used to center thecapsulorrhexis on the limbus as illustrated in FIG. 10A. Alternatively,the outside circle may be sized to facilitate centering on the interiorboundary of the dilated pupil, as represented in FIG. 10B.

FIGS. 11A-11B each show a view of an eye including the limbus 810, iris140, and pupil 190 onto which is projected an example visualizationpattern 1100 comprising two concentric circles or closed curves 1110 and1120 with dots 1130 on the curves and a cross hair 1140. The combinationof lines and dots provides a pattern easily focused on the targettissue. The lines are produced by moving the visualization beam alongthe desired pattern. The dots are produced by dwelling the visualizationbeam for longer periods at the dot locations in the scan pattern. Thedots may provide enhanced visualization on the target tissue becausethey are more intense than the lines. The inner circle or closed curve1110 represents the size and location of the desired opening in theanterior capsulorrhexis. The outer circle 1120, which may be sizedindependently of the inner circle size, may be used to center thecapsulorrhexis on the limbus as illustrated in FIG. 11A. Alternatively,the outside circle may be sized to facilitate centering on the interiorboundary of the dilated pupil, as represented in FIG. 11B. The additionof the cross hair further enhances the ability to focus and center thevisualization pattern.

FIGS. 12A-12L show additional visualization patterns each of which maycomprise a combination of inner 1205, 1210 and outer 1220 closed curves,dots 1230 on the curves, dots 1230 not on curves, a cross-hair 1240,dashed arcs 1250, and/or straight-line segments 1260 forming closedcurves. Generally, the closed visualization curves shown in these andother figures may be formed from straight line segments, which may beeasier to program and/or easier to generate than curved arcs.

FIGS. 13A-13B show an example of an elliptical rhexis 1300 with a majorand a minor axis and a rotation angle. FIGS. 13C-13D show two examplesof visualization patterns that may be used with the elliptical rhexis ofFIGS. 13A-13B. Each pattern comprises a circular outer closed curve andan elliptical inner closed curve (1320 and 1310, respectively, in FIG.13C), dots 1330 on the curves, and a cross hair 1340. In FIG. 13D theclosed curves are formed with straight-line segments 1360. Theelliptical inner closed curves represent the size and location of thedesired opening in the anterior capsulorrhexis. The outer circles, whichmay be sized independently of the inner ellipse size, may be used tocenter the capsulorrhexis on the limbus, for example.

FIG. 14 shows a view of an eye including the limbus 810, iris 140,interior boundary of the iris 820, and pupil 190 onto which is projectedan example visualization pattern comprising two concentric closedcircles or curves with dots 1430 on the curves and a cross hair 1440.The closed curves are formed from straight-line segments 1460. The innercircle or closed curve represents the size and location of the desiredopening in the anterior capsulorrhexis. The outer circle, which may besized independently of the inner circle, may be used to center thecapsulorrhexis on the limbus as illustrated. Alternatively, the outercircle may be sized to facilitate centering on the interior boundary ofthe dilated pupil. This figure also shows the treatment beam pattern1490 for a desired circular rhexis. Treatment beam pattern 1490 differsfrom and is of a smaller diameter than the visualization pattern innerclosed circle.

FIG. 15 shows a view of an eye including the limbus 810, iris 140,interior boundary of the iris 820, and pupil 190 onto which is projectedan example visualization pattern comprising an outer circular closedcurve 1520 and an inner elliptical closed curve 1510, dots 1530 on thecurves, and a cross hair 1540. The elliptical inner closed curvesrepresent the size and location of the desired opening in the anteriorcapsule. The outer circle, which may be sized independently of the innerellipse, may be used to center the capsulorrhexis on the limbus asillustrated. Alternatively, the outer circle may be sized to facilitatecentering on the interior boundary of the dilated pupil. This figurealso shows the treatment beam pattern 1590 for a desired ellipticalrhexis. Treatment beam pattern 1590 differs from and is smaller than thevisualization pattern inner ellipse.

Any other suitable visualization beam patterns may also be used. One ormore visualization beam pattern shapes may be preprogrammed into a lasercapsulorrhexis device (described in more detail below) by themanufacturer, for example. At or prior to the time of treatment anoperator may then, for example, select a pattern size and shape to beused to guide the treatment.

The location of the visual axis relative to center on the limbus ordilated pupil may also be measured on a separate diagnostic device. Theoffset data from center may then also be manually or automatically inputinto the laser capsulorrhexis device. In such cases, the visualizationpattern may be arranged so that when an exterior portion of thevisualization pattern (e.g., a circle) is positioned or centered on theeye anatomy of the limbus or dilated pupil, the center of an interiorportion (e.g., a circle or ellipse) of the visualization pattern isoffset from the center of the limbus or dilated pupil to lie on thevisual axis. The center of the closed curve of the treatment pattern maybe correspondingly offset from the center of the limbus or dilatedpupil, so that the central circle or ellipse of the visualizationpattern indicates the perimeter of the desired rhexis.

The visualization pattern laser beam may have any suitable wavelength inthe visible spectrum. The visualization beam may be scanned across thetissue to be treated at, for example, a speed greater than about 450mm/second, though it may also dwell to form dots or other brighterfeatures in the visualization pattern. Any suitable scanning speeds maybe used. The diameter of the visualization light beam on the tissuesurface may be, for example, about 50 to about 600 microns. Thevisualization laser beam power at the tissue may be, for example, lessthan about 10 mW or less than about 1 mW when the beam is dwelling on adot in the visualization pattern. When the visualization beam isscanning its power may be, for example, less than about 30 mW. Generallythe power and the wavelength of the laser beam are selected to provide asufficiently visible visualization pattern without significantlydepleting any absorbing agent that has been deposited on the tissue tofacilitate treatment.

Treatment Beam and Scanning Parameters

Generally, parameters characterizing the treatment laser beam and thetreatment beam scanning procedure are selected to provide the desiredlaser induced thermal separation of tissue at the treated tissue whileminimizing or reducing the risk of damage to the retina. These laser andscanning parameters may include, for example, laser wavelength, laserbeam power, spot size at the treated tissue, fluence and peakirradiation at the treated tissue, spot size on the retina, fluence andpeak irradiation on the retina, scanning speed, temporal profile of thelaser beam during the scan, and scanning pattern size and location onthe retina.

Typically, a treatment beam from a continuous wave laser traces thetreatment beam pattern in a single pass in a time period of, forexample, less than about 10 seconds, less than about 5 seconds, lessthan about 1 second, about 10 seconds, about 5 seconds, or about 1second. The treatment beam may move across the treated tissue at aspeed, for example, of about 20 millimeters/second (mm/s) for a 1 secondscan to about 2 mm/s for a 10 second scan, but any suitable scanningspeed and duration may be used. The formation of irregularities or tearsin the resulting rim of tissue is reduced or avoided because movement ofthe continuous wave laser beam along the treatment path occurs duringirradiation of the treated tissue (rather than between discrete laserpulses, for example), and thus all portions of the rim are formed withthe same or similar irradiation and thermal conditions. Using a singlepass of the treatment beam also helps to ensure completion of thecapsulorrhexis even if there is slight movement of the eye relative tothe trajectory.

In variations in which the treatment beam path begins on the interior ofthe closed curve of the treatment pattern (see FIG. 4C, for example),the initial scanning speed in the interior portion of the treatment pathmay be less than the scanning speed along the closed curve. The scanningspeed on the interior portion may, for example, ramp up to the speedused along the closed curve. The average speed along the interiorportion may be, for example, about ½ of the scanning speed used alongthe closed curve, or about ⅔ of the scanning speed used along the closedcurve, or between about ½ and about ⅔ of the scanning speed used alongthe closed curve.

Referring now to the plot of laser power versus time shown in FIG. 16for an example treatment beam scan, at the beginning of a treatment scanthe power in the treatment beam may be ramped up slowly (and optionallymonotonically, as shown, to be efficient with time). As noted above inthe summary section, this slow ramp up may allow the tissue near thestarting point of the pattern to initially stretch without separating,thereby reducing the shear stress/tension at the start of the pattern.This slow ramp up may also avoid or minimize local shock waves in thefluid adjacent to the target tissue that might otherwise be generated bya faster thermal turn-on. For example, the laser beam may ramp-upmonotonically from zero to about 90% of full treatment power over aperiod of from about 5 milliseconds (ms) to about 200 ms, for exampleabout 100 ms. This ramp-up of power typically occurs while the laserbeam is scanned along an initial portion of the treatment path. Invariations in which the treatment beam path begins on the interior ofthe closed curve of the treatment pattern (see again FIG. 4C, forexample), the ramp-up in laser beam power may occur along the initialinterior portion of the treatment path and be complete before the laserbeam reaches the closed curve portion of the treatment pattern. In suchvariations the scanning speed of the beam along the initial interiorportion of the treatment path may also ramp up to the speed used alongthe closed curve, as described above. The average speed along theinterior portion of the path may be about 25% of the scanning speed usedalong the closed curve, for example.

As shown in FIG. 16, turn-off of the treatment laser beam pulse at theend of the treatment scan may be much more abrupt than turn-on.

As noted earlier in this specification, the treatment laser beamwavelength may be selected to be strongly absorbed by a light absorbingagent optionally added onto or into the tissue to be treated. Thetreatment laser may operate at a wavelength of about 577 nanometers orabout 810 nanometers, for example. In such examples the light absorbingagent, if used, may be Trypan Blue or Indocyanine Green, respectively.Alternatively, the treatment laser wavelength may be selected to beabsorbed or strongly absorbed by the tissue itself. Any suitablewavelength for the treatment beam may be used.

As described in more detail below, typically the treatment laser beam isfocused to a waist at or near the location of the tissue to be treated,and then expands in diameter as it propagates to the retina. Also,typically the scanning pattern is expanded on the retina compared to itssize on the treated tissue. Consequently, parameters such as fluence andpeak irradiation for the treatment beam may have different and largervalues at the treated tissue compared to their values at the retina.

The methods and devices disclosed herein typically rely on laser inducedthermal separation of tissue rather than on laser induced ablation, andmay therefore use much lower treatment beam fluence and peak irradiationvalues at the treated tissue than typically required by other laserbased surgical procedures. In addition, the methods and devicesdisclosed herein may use treatment laser beams having relatively highaverage power without producing peak irradiation values that arepotentially damaging to the retina or other eye tissue, because thesemethods and devices may use long (e.g., 1 to 10 second) pulses from acontinuous wave laser. In contrast, laser based surgical proceduresusing much shorter Q-switched or mode-locked laser pulses may berequired to operate at much lower average powers to avoid potentiallydamaging peak irradiance values, which may increase the time required toprovide a desired fluence.

The average power of the treatment beam, which is selected depending inpart on the absorption strength of the absorbing agent at the treatmentbeam wavelength or the absorption strength of the treated tissue at thetreatment beam wavelength, may be for example about 300 mW to about 3000mW. Any suitable average power may be used.

The treatment beam fluence on a particular tissue depends on the averagepower in the treatment beam, the diameter of the treatment beam at thattissue, and the scanning speed of the treatment beam across that tissue.For the methods and devices disclosed herein, at the tissue to betreated (e.g., the anterior lens capsule) the treatment beam fluence fora 1 second scan may be for example about 80 Joules/centimeter² (J/cm²)to about 450 J/cm². For a 5 second scan the fluence at the tissue to betreated may be for example about 100 J/cm² to about 1600 J/cm². For a 10second scan the fluence at the tissue to be treated may be for exampleabout 100 J/cm² to about 2000 J/cm².

The treatment beam peak irradiance on particular tissue depends on thepeak power in the treatment beam and the diameter of the treatment beamat that tissue. For the methods and devices disclosed herein, at thetissue to be treated (e.g., the anterior lens capsule) the treatmentbeam peak irradiance may be, for example, less than about 50,000Watt/centimeter² (W/cm²), or less than about 100,000 W/cm², or less thanabout 150,000 W/cm², or less than about 200,000 W/cm².

In general, at the retina the treatment beam fluence is less than about200 J/cm² and the irradiance is less than about 2000 W/cm². In oneembodiment with an NA of about 0.03 and a beam diameter of about 1,400microns on the retina, for a 1 second scan speed for example, thefluence at the retina has a maximum of about 5 J/cm². For a 5 secondscan the fluence at the retina may for example have a maximum of about25 J/cm². For a 10 second scan the fluence at the retina may for examplehave a maximum of about 50 J/cm². The irradiance may have for example amaximum for example of about 200 W/cm² on the retina, across these 1, 5and 10 second scan speeds for a system with an NA of about 0.03.

Referring now to FIG. 17, the inventor has discovered that the minimumtreatment laser beam power required for laser induced separation oftissue has a non-linear response to the irradiated beam area on thetreated tissue. In particular, this plot demonstrates that there is alow dependence of the power required for tissue separation on the sizeof the irradiated area, specifically below about a beam diameter ofabout 100 to about 200 microns. However, as the spot size increases farabove a diameter of about 300 microns, more power is required toseparate tissue.

Hence it may be preferable to use a treatment beam having a diameter ofabout 200 microns at the treated tissue. This may reduce the requiredirradiance in the treatment beam and thus decrease the risk of damagingthe retina. More generally, the treatment laser beam may have a diameterof, for example, about 50 microns to about 400 microns at the treatedtissue.

Use of Surgical Contact Lens

A surgical contact lens may be used to neutralize or approximatelyneutralize the cornea's focusing power on the retina to further reducerisk of damaging the retina, and in particular to protect the fovea.(The fovea is located in the center of the macula region of the retina,and is responsible for sharp central vision). FIG. 18A demonstrates thatin the absence of a surgical contact lens, a scanned treatment laserbeam pattern 1800 centered around the visual axis 1810 would be focusedinto the proximity of the fovea 1820 on the retina. It is likely thatthe fovea would be under constant irradiation for the full duration ofthe scanned pattern. FIG. 18B demonstrates that in the presence of asurgical contact lens 1830 with a mild convex anterior surface 1840minimizing the majority of the corneal optical lens power, a scannedlaser beam pattern 1800 centered around the visual axis 1810 may beprojected onto the retina such that it avoids the fovea and insteadsurrounds the fovea. FIG. 18C demonstrates that in the presence of asurgical contact lens 1830 with a concave anterior surface 1850, ascanned laser beam pattern 1800 centered around the visual axis may beprojected on to the retina so that it avoids the fovea and insteadsurrounds the fovea. Moreover, the trace of the laser beam projected onto the retina may be further refracted way from the fovea than would bethe case for a convex surgical contact lens. In addition the areairradiated by the laser beam would be larger on the retina, whichreduces the delivered laser energy per unit area (fluence) on theretina.

Use of a surgical contact lens as just described to refract the scannedtreatment beam pattern away from the fovea allows the treatment laser tobe operated at a higher power, without damaging the fovea or otherportions of the retina, than might otherwise be the case. Such use of asurgical contact lens is optional, however.

Treatment/Scanning Device

Referring now to FIG. 19, an example device 1900 may be used to performophthalmic surgeries as described herein. FIG. 19 illustrates theoptical beam focusing and the scanner optical properties of this device.Device 1900 comprises an optical fiber 1910 that delivers collinearvisualization and treatment laser beams 1920 (e.g., from treatment laser1922 and visualization laser 1924) to a lens 1930, which focuses thebeams beyond a two-dimensional scanner 1940. The two-dimensional scanner1940 scans the visualization or treatment laser beam to provide thedesired visualization or treatment beam pattern. Lens 1950 focuses thetreatment and visualization laser beams to a waist in the treated eye1960 at or approximately at the anterior lens capsule 1970. Afterpassing through that waist the laser beams expand and are thus defocusedon the retina. Optional stationary final mirror 1980 may be used asshown to direct the beams to be collinear or nearly collinear withmicroscope optics (see FIGS. 20-21).

The two-dimensional scanner 1940 has different tilt positions to createa scanned pattern on the anterior capsule. The solid line depiction ofthe scanner represents one example tilt position, and the dash linedepiction of the scanner represents a second tilt position. In thisexample device the optics are designed such that there is a scannerpattern invariant 1985 (a location at which there is no apparent motionof the scanned pattern) and waist between the lens 1950 and its focus.Compared to a system lacking a scanner pattern invariant located in thismanner, this arrangement has the advantages of reducing or minimizingthe size of the optical device, reducing or minimizing the requiredtwo-dimensional scanner tilt, reducing or minimizing the area requiredon the optional final mirror, and providing additional divergence of thescanned pattern along the optical path so that for the same size andshape pattern on the anterior capsule, the projection on the retina hasa larger diameter and therefore less fluence and less associatedtemperature rise at the retina.

Example device 1900 also includes an optional light detector 1990. Thetwo-dimensional scanner 1940 may deflect the treatment or visualizationlaser beams to detector 1990, which may be used for example to measuretheir power. Detector 1990 may be a detector array, for example, inwhich case the two-dimensional scanner 1940 may scan the treatment orvisualization laser beam across the detector array to confirm that thescanner is functioning properly.

Device 1900 further includes an optional aberrometer 1995, which may beused to make refractive measurements of the eye to be treated. This maybe accomplished, for example, by tilting the two-dimensional scanner1940 to direct an output light beam from aberrometer 1995 along theoptical path used for the visualization and treatment beams into theeye. Alternatively, a light beam from aberrometer 1995 could optionallybe introduced into the optical path of device 1900 with a dichroic beamsplitter, for example.

Device 1900 includes a scanner controller 1928. The scanner controllermay be preprogrammed with one or more treatment beam pattern shapes andone or more visualization pattern shapes by the manufacturer, forexample. At or prior to the time of treatment an operator may then, forexample, select treatment and visualization pattern sizes and shapes tobe used in a particular treatment procedure.

Any other suitable device design may also be used to perform theprocedures described herein.

Integration with Microscope

Example device 1900 described above may be integrated with a microscope.FIG. 20 shows an example in which device 1900 is externally integratedwith a microscope 2000. The integration is external because device 1900and microscope 2000 do not share any optical elements. Microscope 2000may be used by a human operator 2010 (eye only shown) to observe the eye1960 to be treated and the visualization pattern prior to, during, andafter the treatment procedure.

FIG. 21 shows an example in which device 1900 of FIG. 19 is internallyintegrated with a microscope to provide an integrated device 2100. Inthis integrated device, the treatment and visualization beam paths passthrough the microscope objective 2110, and illumination for themicroscope is provided by light output from an optical fiber 2120 alonga path that shares stationary mirror 1980 with the treatment andvisualization beam paths.

Any other suitable integration with a microscope may also be used.

Depth Alignment

A preliminary step in using device 1900 is to adjust the position of thedevice, or of the optical elements within the device, with respect tothe patient's eye so that the waist (focus) of the treatment beam is ator approximately at the tissue to be treated. This may be done, forexample, by viewing a visualization pattern (e.g., as described above)that is projected onto the tissue to be treated and adjusting device1900 to bring the visualization pattern into focus on the tissue.However, in this approach any uncorrected deficiency in the operator'svision (e.g., myopia) may affect the operator's judgment as to whetheror not the visualization pattern is in focus on the tissue to betreated. This may result in an incorrect adjustment of the treatmentdevice.

Referring now to FIG. 22, an example device 2200 for performingophthalmic surgeries includes, in addition to the elements of device1900 shown in FIG. 19, optical elements that produce a secondvisualization beam to facilitate depth alignment of the device. Inparticular, in a depth alignment mode, further described below, scanner1940 in device 2200 dithers to direct a visible light visualization beam1920 from optical fiber 1910 along two different optical paths toproduce visualization beams 2210 and 2215. Scanner 1940 may ditherbetween the two paths at a rate greater than or equal to about 30 Hertz,for example, so that flickering of the two beams is not typicallynoticeable to an operator.

Beam 2210 follows the optical path of the treatment and visualizationlaser beams described above with respect to FIG. 19, and may be scannedto produce any suitable pattern. Beam 2215 may also be scanned toproduce any suitable pattern. Beam 2215 is directed to intersect beam2210 at or approximately at the treatment beam waist. As furtherdescribed below, the intersection of beams 2210 and 2215 may thereforebe used to identify the location of the treatment beam waist and todetermine whether or not the treatment beam waist is properly positionedat the tissue to be treated. In the illustrated example, beam 2215 isdirected to intersect beam 2210 using mirror 2220 and lens 2230 but anyother suitable optical arrangement producing the desired intersectionmay also be used. Lens 2230 typically focuses beam 2215 to a tight waistat the intersection of the two beams, to identify the location of thatintersection with greater precision.

If the intersection of beams 2210 and 2215 (and thus the treatment beamwaist) is not properly positioned at the treatment tissue, the positionof device 2200 or of optical elements within the device may be adjustedwith respect to the patient's eye to move the intersection of thevisualization beams, and thus the treatment beam waist, to the desiredposition.

Referring now to FIGS. 23A-23C, in some variations beam 2210 is scannedto produce a line 2310 and beam 2215 is not scanned but instead focusedto a tight waist that appears as a dot 2315 in these figures. Device2200 is aligned (e.g., by the manufacturer) so that beams 2210 and 2215intersect at or approximately at the location of the waist of thetreatment beam, with the dot 2315 centered or approximately centered online 2310. FIGS. 23A-23C show a view through a microscope (e.g.,microscope 2000 of FIG. 20) of the tissue to be treated (e.g., the lenscapsule). When the intersection of visualization beams 2210 and 2215 isnot positioned at or approximately at the tissue to be treated, dot 2315and line 2310 will appear to be displaced from each other as shown inFIGS. 23A-23B. Further, an operator may be able to determine whether thevisualization beams intersect in front of or behind the tissue to betreated based on which side of line 2310 the dot 2315 appears to belocated. After device 2200 is adjusted to position the intersection ofbeams 2210 and 2215 (and therefore the waist of the treatment beam) ator approximately at the tissue to be treated, line 2310 and dot 2315will appear superimposed as shown in FIG. 23C.

Although the illustrated example uses a line 2310 and a dot 2315, anyother suitable patterns for intersecting beams 2210 and 2215 may be usedto identify and adjust the position of the treatment beam waist withrespect to the tissue to be treated. Typically the visualizationpatterns used in depth alignment mode differ from those describedearlier in this specification. Although in the illustrated exampleintersecting beams 2210 and 2215 are produced from a singlevisualization laser beam by dithering the scanner 1940, any othersuitable method of intersecting visible beams to identify the locationof the treatment beam waist may also be used. Beams 2210 and 2215 mayhave the same wavelength, as in the example just described, or differentwavelengths.

Device 2200 may be switchable between several different operating modesincluding the depth alignment mode just described. For example, in somevariations device 2200 may be switchable between at least the followingmodes:

-   -   Standby Mode: The treatment beam and all visualization beams are        off.    -   Depth Alignment Mode: As described above, intersecting        visualization beams are used to facilitate adjusting the        position of the focus of the treatment beam optical system with        respect to the position of the tissue to be treated. The        treatment beam is not activated.    -   Ready Mode: Visualization patterns are projected onto the lens        capsule to guide the treatment. The visualization patterns may        facilitate alignment of the treatment beam with respect to        anatomy of the eye, and/or indicate the desired perimeter of a        rhexis to be produced with the treatment beam.    -   Fire Mode: Treatment laser beam emission is activated and        incident on the tissue to be treated.

Referring to FIG. 24A, some variations of device 2200 may include afoot-operable control 2400 in which a first button 2405, located on topof shroud 2410 for example, may be activated to switch from Standby toDepth Alignment Mode, with the device remaining in Depth Alignment Mode.Button 2405 may be activated again to switch from Depth Alignment Modeto Ready Mode, with the device remaining in Ready Mode. While the deviceis in Ready Mode, a shrouded fire button 2415 may be activated to switchfrom Ready Mode to Fire Mode, activating the treatment beam and thetreatment beam scan, after which the device returns to Standby Mode.Alternatively, button 2405 may be activated again to switch from ReadyMode to Standby Mode.

Some variations of device 2220 may also be switchable into and out of aVisualization Sizing Mode. In the Visualization Sizing Mode, avisualization sizing pattern is projected onto the anterior lens capsuleto guide positioning of the desired rhexis and thus positioning of thedesired closed curve of the treatment beam. The size (e.g., diameter oranother dimension) of the visualization sizing pattern is adjustable toincrease or decrease a corresponding dimension of the desired rhexis tobe formed by the treatment beam. In these variations, the device may beswitched between modes in the following order, for example: StandbyMode, Depth Alignment Mode, Visualization Sizing Mode, Ready Mode,Standby Mode. This may be done, for example, by sequential activation ofbutton 2405 (FIG. 24A) as described above. The visualization sizingpattern projected during Visualization Sizing Mode may have the samegeometry as the visualization pattern projected in Ready Mode, or bedifferent. It may be advantageous for the visualization sizing patternto differ in geometry from the visualization pattern, to make it easierfor an operator to recognize in which mode the device is in.

Referring to FIG. 24B, foot operable control 2400 may further includebuttons 2420A and 2420B, located on interior or exterior side walls ofthe shroud for example, that may be used to increase or decrease thesize of the visualization pattern projected during Visualization SizingMode (and correspondingly increase or decrease the desired radius oranother dimension of the rhexis to be formed by the treatment beam).

Any other suitable switching mechanism may be used to switch between theoperating modes just described. The switching mechanism may be orinclude switches intended to be hand operated, for example. Further,variations of foot-operable control 2400 described above, or of anyother suitable switching mechanism, may be configured to allow thedevice to be switched from Depth Alignment Mode to Standby Mode, fromVisualization Sizing Mode (if available) to Depth Alignment Mode, orfrom Ready Mode to Visualization Mode (if available) or Depth AlignmentMode. This may be accomplished using additional switching buttons forthese transitions, for example, or with a button that reverses thedirection in which button 2405 moves the device through the sequence ofmodes.

Detecting a Light Absorbing Agent

In variations of the procedures described herein in which a lightabsorbing agent is used to facilitate laser assisted thermal tissueseparation, it may be desirable to optically or visually confirm thatthe light absorbing agent has been correctly placed prior to performingthe treatment. This may be done, for example, with a detection laserbeam having a wavelength selected to be reflected rather than absorbedby the light absorbing agent (and thus different from the wavelength ofthe treatment beam). For example, if the light absorbing agent is TrypanBlue the detection beam may be chosen to have a wavelength in the blueregion of the visible spectrum. Alternatively, the light absorbing agentmay be detected with the treatment beam by exciting and detectingfluorescence from the light absorbing agent. In the latter case themeasurement may preferably be made at a position away from the treatmentlocation to avoid depleting light absorbing agent required for thetreatment scan.

Reflected light or fluorescence indicating the presence of the lightabsorbing agent may be observed or detected, for example, through amicroscope integrated with the treatment device as described above. Adetection laser beam (e.g., from detection laser 1926 in FIG. 19) usedin such a reflectance measurement may be introduced through the sameoptical fiber that delivers the treatment and visualization beams.

This disclosure is illustrative and not limiting. Further modificationswill be apparent to one skilled in the art in light of this disclosureand are intended to fall within the scope of the appended claims. Forexample, in some variations pulsed lasers may be use instead ofcontinuous wave lasers to produce visualization and/or treatment laserbeams in the methods and devices described above.

What is claimed is:
 1. A device for creating an opening in the anteriorlens capsule of the eye, the device comprising: a treatment laseroutputting a treatment laser beam; a visualization laser outputting avisualization laser beam; a two-dimensional scanner on which thetreatment laser beam and the visualization laser beam are incident; anda scanner controller controlling the two-dimensional scanner, thescanner controller having one or more programmed scan profiles forpredetermined treatment patterns in which the treatment laser beam isscanned to form a closed curve at the anterior lens capsule and one ormore corresponding programmed scan profiles for predeterminedvisualization patterns in which the visualization laser beam is scannedto form the predetermined visualization pattern at the anterior lenscapsule; wherein the treatment laser beam has a wavelength absorbed byTrypan Blue or Indocyanine Green, a spot size at the anterior lenscapsule of less than 300 microns, and a power of 300 milliwatts to 3000milliwatts, and absorption of 35% or more of the treatment laser beampower at the anterior lens capsule causes thermal denaturing of collagenin the anterior lens capsule resulting in thermal tissue separationalong the closed curve to form the opening without ablating anteriorlens capsule tissue; and wherein for each programmed scan profile forthe treatment laser beam the corresponding programmed scan profile forthe visualization laser beam scans the visualization laser to form avisualization pattern at least a portion of which represents the sizeand location of a perimeter boundary of the opening to be created in theanterior lens capsule by the treatment laser beam and matches at least aportion of the perimeter boundary, the perimeter boundary of the openingdiffering in size and location from the closed curve of thecorresponding treatment pattern and having a larger diameter than theclosed curve of the corresponding treatment pattern.
 2. The device ofclaim 1, wherein at least a portion of the visualization patterncorresponds to the pupil or the limbus of the eye, and therebyfacilitates aligning the treatment pattern with respect to thoseanatomical features.
 3. The device of claim 1, wherein the treatmentlaser is a continuous wave laser, the treatment laser beam is scannedalong the closed curve of the treatment pattern in a single pass, andthe power of the treatment laser beam is constant along the closedcurve.
 4. The device of claim 1, wherein scanning the treatment laserbeam is completed in less than or equal to 10 seconds.
 5. The device ofclaim 4, wherein scanning the treatment laser beam is completed in lessthan or equal to 5 seconds.
 6. The device of claim 5, wherein scanningthe treatment laser beam is completed in less than or equal to 1 second.7. The device of claim 1, wherein the treatment laser beam is focused toa waist at the anterior lens capsule and diverges as it is incident onthe retina of the eye, and the treatment pattern diverges in the eye andis consequently expanded in size and area on the retina compared to itssize and area at the anterior lens capsule.
 8. The device of claim 7,wherein the treatment laser beam provides a fluence of less than orequal to 2000 J/cm² along the closed curve of the treatment pattern atthe anterior lens capsule and a fluence of less than or equal to 200J/cm² along a corresponding closed curve on the retina of the eye. 9.The device of claim 7, wherein the treatment laser beam provides a peakirradiance of less than or equal to 100,000 W/cm² along the closed curveof the treatment pattern at the anterior lens capsule and a peakirradiance of less than or equal to 2000 W/cm² along a correspondingclosed curve on the retina of the eye.
 10. The device of claim 7,wherein the treatment laser beam has a diameter of greater than or equalto 100 microns and less than 300 microns at the anterior lens capsule.11. The device of claim 7, wherein the treatment pattern on the retinaavoids the fovea of the eye.
 12. The device of claim 1, wherein at thebeginning of the treatment pattern the power of the treatment laser beamramps up from zero to 90% of its full power during a period of 5milliseconds to 200 milliseconds.
 13. The device of claim 12, whereinthe treatment laser beam is scanned from an initial point inside theclosed curve toward the closed curve at a speed less than an averagespeed at which the treatment laser beam is subsequently scanned alongthe closed curve, and the ramp-up of treatment laser beam power iscomplete before the treatment laser beam reaches the closed curve. 14.The device of claim 1, comprising a detection laser outputting adetection laser beam having a wavelength that is reflected by TrypanBlue or Indocyanine Green.
 15. The device of claim 1, comprising adetection laser outputting a detection laser beam having a wavelengththat excites fluorescence from Trypan Blue or Indocyanine Green.
 16. Thedevice of claim 1, arranged in combination with a surgical contact lenspositioned on the eye to neutralize the focusing power of the cornea ofthe eye on the retina of the eye and refract the scanning pattern awayfrom the fovea of the eye.
 17. The device of claim 1, integrated with amicroscope.
 18. The device of claim 1, integrated with an aberrometerconfigured to measure refractive properties of the eye.
 19. The deviceof claim 1, comprising: a first lens positioned before thetwo-dimensional scanner along the optical path of the treatment laserbeam; and a second lens positioned after the two-dimensional scanneralong the optical path of the treatment laser beam; wherein the firstlens focuses the treatment laser beam to a first waist between the twodimensional scanner and the second lens; wherein the second lens focusesthe treatment laser beam to a second waist at the anterior lens capsuleand the treatment laser beam expands from its second waist to bedefocused on the retina of the eye; and wherein the second lens focusesthe treatment pattern to a waist between the second lens and the eye,and the treatment pattern diverges in the eye and is consequentlyexpanded in size and area on the retina compared to its size and area atthe anterior lens capsule.